This article is cited in 18 papers

Semiconductors

Specific features of electrical properties of porous biocarbons prepared from beech wood and wood artificial fiberboards

V. V. Popov^a, T. S. Orlova^a, E. Enrique Magarino^b, M. A. Bautista^b, J. Martínez-Fernández<sup>b

a</sup> Ioffe Institute, St. Petersburg
^b Universidad de Sevilla, Sevilla, Spain

Abstract: This paper reports on comparative investigations of the structural and electrical properties of biomorphic carbons prepared from natural beech wood, as well as medium-density and high-density fiberboards, by means of carbonization at different temperatures $T_{\mathrm{carb}}$ in the range 650–1000$^\circ$C. It has been demonstrated using X-ray diffraction analysis that biocarbons prepared from medium-density and high-density fiberboards at all temperatures $T_{\mathrm{carb}}$ contain a nanocrystalline graphite component, namely, three-dimensional crystallites 11–14 $\mathring{\mathrm{A}}$ in size. An increase in the carbonization temperature $T_{\mathrm{carb}}$ to 1000$^\circ$C leads to the appearance of a noticeable fraction of two-dimensional graphene particles with the same sizes. The temperature dependences of the electrical resistivity $\rho$ of the biomorphic carbons have been measured and analyzed in the temperature range 1.8–300 K. For all types of carbons under investigation, an increase in the carbonization temperature $T_{\mathrm{carb}}$ from 600 to 900$^\circ$C leads to a change in the electrical resistivity at $T$ = 300 K by five or six orders of magnitude. The dependences $\rho(T)$ for these materials are adequately described by the Mott law for the variable-range hopping conduction. It has been revealed that the temperature dependence of the electrical resistivity exhibits a hysteresis, which has been attributed to thermomechanical stresses in an inhomogeneous structure of the biocarbon prepared at a low carbonization temperature $T_{\mathrm{carb}}$. The crossover to the conductivity characteristic of disordered metal systems is observed at $T_{\mathrm{carb}}\gtrsim$ 1000$^\circ$C.

 English version: Physics of the Solid State, 2011, 53:2, 276–283

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